Technical Abstract:
Livestock producers need tools to predict diet quality of free-ranging animals to develop supplementation strategies and to predict animal performance on warm season grass pastures. Current laboratory methods generally require sample collection, processing time of days to weeks, and may involve hazardous chemical wastes. The objective of this experiment was to compare real-time, remote sensing-based assessments of crude protein (CP) concentration of live, standing forage with conventional laboratory methods. Beginning on June 1, 2003 canopy reflectances from four 1.6-ha bermudagrass pastures were measured each week throughout the growing period and converted into estimates of CP concentration. These estimates were compared to CP concentrations determined by combustion nitrogen analysis of clipped, dried and ground forage samples of the area viewed by the remote sensing device. Repeated measures analysis indicated that there was no difference between CP determination methods (P > 0.47). Early in the growing season average CP concentration varied from 8% to 10%, depending upon pasture, declining to about 5% in all pastures at the end of the study. The remote sensing method provides rapid assessment of forage quality compared to conventional laboratory methods, which would allow producers to recognize dietary nutrient deficiencies in a timely manner to preclude a decrease in livestock performance.